package net.iasolution.jpay.server.util;

public class URIUtil {

	final static String[] hex = { "%00", "%01", "%02", "%03", "%04", "%05", "%06", "%07", "%08", "%09", "%0a", "%0b", "%0c", "%0d", "%0e", "%0f", "%10", "%11", "%12", "%13", "%14", "%15", "%16",
			"%17", "%18", "%19", "%1a", "%1b", "%1c", "%1d", "%1e", "%1f", "%20", "%21", "%22", "%23", "%24", "%25", "%26", "%27", "%28", "%29", "%2a", "%2b", "%2c", "%2d", "%2e", "%2f", "%30",
			"%31", "%32", "%33", "%34", "%35", "%36", "%37", "%38", "%39", "%3a", "%3b", "%3c", "%3d", "%3e", "%3f", "%40", "%41", "%42", "%43", "%44", "%45", "%46", "%47", "%48", "%49", "%4a",
			"%4b", "%4c", "%4d", "%4e", "%4f", "%50", "%51", "%52", "%53", "%54", "%55", "%56", "%57", "%58", "%59", "%5a", "%5b", "%5c", "%5d", "%5e", "%5f", "%60", "%61", "%62", "%63", "%64",
			"%65", "%66", "%67", "%68", "%69", "%6a", "%6b", "%6c", "%6d", "%6e", "%6f", "%70", "%71", "%72", "%73", "%74", "%75", "%76", "%77", "%78", "%79", "%7a", "%7b", "%7c", "%7d", "%7e",
			"%7f", "%80", "%81", "%82", "%83", "%84", "%85", "%86", "%87", "%88", "%89", "%8a", "%8b", "%8c", "%8d", "%8e", "%8f", "%90", "%91", "%92", "%93", "%94", "%95", "%96", "%97", "%98",
			"%99", "%9a", "%9b", "%9c", "%9d", "%9e", "%9f", "%a0", "%a1", "%a2", "%a3", "%a4", "%a5", "%a6", "%a7", "%a8", "%a9", "%aa", "%ab", "%ac", "%ad", "%ae", "%af", "%b0", "%b1", "%b2",
			"%b3", "%b4", "%b5", "%b6", "%b7", "%b8", "%b9", "%ba", "%bb", "%bc", "%bd", "%be", "%bf", "%c0", "%c1", "%c2", "%c3", "%c4", "%c5", "%c6", "%c7", "%c8", "%c9", "%ca", "%cb", "%cc",
			"%cd", "%ce", "%cf", "%d0", "%d1", "%d2", "%d3", "%d4", "%d5", "%d6", "%d7", "%d8", "%d9", "%da", "%db", "%dc", "%dd", "%de", "%df", "%e0", "%e1", "%e2", "%e3", "%e4", "%e5", "%e6",
			"%e7", "%e8", "%e9", "%ea", "%eb", "%ec", "%ed", "%ee", "%ef", "%f0", "%f1", "%f2", "%f3", "%f4", "%f5", "%f6", "%f7", "%f8", "%f9", "%fa", "%fb", "%fc", "%fd", "%fe", "%ff" };
	
	/**
	 * Encode a string to the "x-www-form-urlencoded" form, enhanced with the
	 * UTF-8-in-URL proposal. This is what happens:
	 * 
	 * <ul>
	 * <li>
	 * <p>
	 * The ASCII characters 'a' through 'z', 'A' through 'Z', and '0' through
	 * '9' remain the same.
	 * 
	 * <li>
	 * <p>
	 * The unreserved characters - _ . ! ~ * ' ( ) remain the same.
	 * 
	 * <li>
	 * <p>
	 * The space character ' ' is converted into a plus sign '+'.
	 * 
	 * <li>
	 * <p>
	 * All other ASCII characters are converted into the 3-character string
	 * "%xy", where xy is the two-digit hexadecimal representation of the
	 * character code
	 * 
	 * <li>
	 * <p>
	 * All non-ASCII characters are encoded in two steps: first to a sequence of
	 * 2 or 3 bytes, using the UTF-8 algorithm; secondly each of these bytes is
	 * encoded as "%xx".
	 * </ul>
	 * 
	 * @param s
	 *            The string to be encoded
	 * @return The encoded string
	 */
	public static String encode(String s) {
		if(s==null)
			return null;
		StringBuffer sbuf = new StringBuffer();
		int len = s.length();
		for (int i = 0; i < len; i++) {
			int ch = s.charAt(i);
			if ('A' <= ch && ch <= 'Z') { // 'A'..'Z'
				sbuf.append((char) ch);
			} else if ('a' <= ch && ch <= 'z') { // 'a'..'z'
				sbuf.append((char) ch);
			} else if ('0' <= ch && ch <= '9') { // '0'..'9'
				sbuf.append((char) ch);
			} else if (ch == ' ') { // space
				sbuf.append('+');
			} else if (ch == '-' || ch == '_' // unreserved
					|| ch == '.' || ch == '!' || ch == '~' || ch == '*' || ch == '\'' || ch == '(' || ch == ')') {
				sbuf.append((char) ch);
			} else if (ch <= 0x007f) { // other ASCII
				sbuf.append(hex[ch]);
			} else if (ch <= 0x07FF) { // non-ASCII <= 0x7FF
				sbuf.append(hex[0xc0 | (ch >> 6)]);
				sbuf.append(hex[0x80 | (ch & 0x3F)]);
			} else { // 0x7FF < ch <= 0xFFFF
				sbuf.append(hex[0xe0 | (ch >> 12)]);
				sbuf.append(hex[0x80 | ((ch >> 6) & 0x3F)]);
				sbuf.append(hex[0x80 | (ch & 0x3F)]);
			}
		}
		return sbuf.toString();
	}

	public static String decode(String s) {
		if(s==null)
			return null;
		StringBuffer sbuf = new StringBuffer();
		int l = s.length();
		int ch = -1;
		int b, sumb = 0;
		for (int i = 0, more = -1; i < l; i++) {
			/* Get next byte b from URL segment s */
			switch (ch = s.charAt(i)) {
			case '%':
				ch = s.charAt(++i);
				int hb = (Character.isDigit((char) ch) ? ch - '0' : 10 + Character.toLowerCase((char) ch) - 'a') & 0xF;
				ch = s.charAt(++i);
				int lb = (Character.isDigit((char) ch) ? ch - '0' : 10 + Character.toLowerCase((char) ch) - 'a') & 0xF;
				b = (hb << 4) | lb;
				break;
			case '+':
				b = ' ';
				break;
			default:
				b = ch;
			}
			/* Decode byte b as UTF-8, sumb collects incomplete chars */
			if ((b & 0xc0) == 0x80) { // 10xxxxxx (continuation byte)
				sumb = (sumb << 6) | (b & 0x3f); // Add 6 bits to sumb
				if (--more == 0)
					sbuf.append((char) sumb); // Add char to sbuf
			} else if ((b & 0x80) == 0x00) { // 0xxxxxxx (yields 7 bits)
				sbuf.append((char) b); // Store in sbuf
			} else if ((b & 0xe0) == 0xc0) { // 110xxxxx (yields 5 bits)
				sumb = b & 0x1f;
				more = 1; // Expect 1 more byte
			} else if ((b & 0xf0) == 0xe0) { // 1110xxxx (yields 4 bits)
				sumb = b & 0x0f;
				more = 2; // Expect 2 more bytes
			} else if ((b & 0xf8) == 0xf0) { // 11110xxx (yields 3 bits)
				sumb = b & 0x07;
				more = 3; // Expect 3 more bytes
			} else if ((b & 0xfc) == 0xf8) { // 111110xx (yields 2 bits)
				sumb = b & 0x03;
				more = 4; // Expect 4 more bytes
			} else /* if ((b & 0xfe) == 0xfc) */{ // 1111110x (yields 1 bit)
				sumb = b & 0x01;
				more = 5; // Expect 5 more bytes
			}
			/* We don't test if the UTF-8 encoding is well-formed */
		}
		return sbuf.toString();
	}

}
